Document current SDK installation and stable API contract selection

Author: billyoshall

README.md

@@ -17,7 +17,7 @@ Get a key at [parseapi.com](https://parseapi.com). `Client::from_env()` reads `P
 
 ## API versions
 
-Version 2.0.0 sends `Parse-Version: 2.0.0` on every request, including retries. Its response types match API `2.0.0`, and the client selects that contract automatically. No extra constructor setting or key change is needed. This behavior requires the matching API request-version release.
+This SDK sends `Parse-Version: 2.0.0` on every request, including retries. Its response types match API `2.0.0`, and the client selects that contract automatically. No extra constructor setting or key change is needed. This behavior requires the matching API request-version release.
 
 The team setting in [Dashboard API version](https://parseapi.com/dashboard/versions) is the default for requests without a version header. This SDK's header takes precedence without changing that saved default. Existing published packages keep their documented behavior.